Inhibition of the Mtorc Pathway in the Antiphospholipid Syndrome

SARA ARANGO VALENCIAMEDICINE STUDENTUPB2014

INTRODUCTIONGENERALITIES

The Antiphospolipid Syndrome is an autoinmune disease characterized by the presence of circulating anthiphospolipid antibodies that result in vascular thrombosis and obstetrical complications.

May be isolated or may occur in association with autoinmune disorders Systemic lupus erythematosus

mTOR (mammalian Target of Rapamycin) is a serine / threonine kinase.

TOR family involved in regulating transcription initiation of the mRNA and the translate into protein in response to intracellular concentrations of amino acids and other nutrients.

mTOR has 2 complexes:

1. Complex sensitive to rapamycin (mTOR-1 or mTORC1), which interacts with Raptor ("regulatory-associated protein of mTOR") proteins.

2. A rapamycin-insensitive complex (mTOR2 or mTORC2) proteins wich is defined by its interaction with rictor ("rapamycin-insensitive companion of mTOR"). Also controls the actin cytoskeleton and Akt/ PKB.

INTRODUCTION

INTRODUCTION1. cytoskeletal organization2.growth and

cell cycle

membrane transport

protein degradati

on

PKC signaling

ribosome biogenesi

s

INTRODUCTIONM TORCH Pathway

The PI3K/AKT/MTOR pathway is an intracellular signaling pathway important in apoptosis and hence cancer.

The PI3K/AKT/MTOR pathway contributes to hypertrophic muscle growth. It is activated by IGFI and has a number of downstream effects which either promote protein synthesis or inhibit protein breakdown.

PI3K activation activates AKT which activates mTOR.

INTRODUCTION

Syndrome – Pathway relationship The vascular endotelium of proliferating intrarenal vessels

from patiens with antiphospholipid syndrome nephropathy showed indications of activation of the m-TORC pathway.

In cultured vascular endothelial cells, IgG antibodies from patients with the anthiphospolipid syndrome stimulated m-TORC through the phosphatidyl-inositol 3-kinase (PI3K)-AKT pathway.

OBJECTIVE m – TOR Pathway

Find the relation of the mTORC Pathway with antiphospholipid syndrome, its regulation and inhibition studies using antibodies, growth factors, and molecules that activated it, in different circumstances.

METODOLOGÍA

1.• Doble inmunotincion para evaluar activación de la vía Mtorc y

la proliferación celular.

2.• Evaluaron autopsias de humanos con el síndrome

antifosfolipidico catastrófico.

3.• Se estudiaron in vitro, las moléculas que modulan la vía Mtorc.

4.• Se estudio el efecto de sirolimus en trasplantes de riñones con

el sindrome.

METODOLOGIAWestern Blot

técnica usada para detectar proteínas específicas en una muestra determinada. Mediante una electroforesis en gel se separan las proteínas atendiendo al criterio que se desee: peso molecular, estructura, hidrofobicidad, etc.

Luego son transferidas a una membrana absorbente para poder buscar la proteína de interés con anticuerpos específicos contra ella. 

Luego se detecta la unión antígeno-anticuerpo por actividad enzimática. Fluorescencia entre otros métodos.

De esta forma se puede estudiar la presencia de la proteína en el extracto y analizar su cantidad relativa respecto a otras proteínas.

METODOLOGIAInmunohistoquimica

Corresponde a un grupo de técnicas de inmunotinción que permiten demostrar una variedad de antígenos presentes en las células o tejidos utilizando anticuerpos marcados. Estas técnicas se basan en la capacidad de los anticuerpos de unirse específicamente a los correspondientes antígenos. Esta reacción es visible sólo si el anticuerpo está marcado con una sustancia que absorbe o emite luz o produce coloración.

RESULTADOS

DISCUSSION• AntiHLA antibodies were

also associated with neointimal hyperplasia, the proliferation of vascular smooth- muscle cells, and Mtorc pathway activation.

Lepin EJ, Zhang Q,

Zhang X, et al.

• It has been shown that antiphospholipids antibodies first associate with B2- glycoprotein I

Laat B, Derksen RH, van LummelM, Pennings MT, de Groot

PG.• and then bind to membrane

receptors that mediate extracellular signalin, ultimately activating endothelial cells and platelets.

Allen KL, Fonseca FV, Betapudi V,

Willard B, Zhang J,

McCrae KR.

YES

YES

YES

• Our data indicate that a different signaling pathway is involved in the development of intimal hyperplasia and suggest that m TORC plays a crucial rol.

Poulton K, Rahman A,

Giles I.

• In the context of thtombosis, p38 mitogen activated protein kinase and nuclear factor kB have been shown to be critical intermediates.

Ramesh S, Morrell CN,

Tarango C, etal.

• In this study, all the serum specimens that we examined from patients with the antiphospholipid syndrome contained a mixture of anti-B2-glycoprotein I, cardiolipin, and anti-lupus anticoagulant antibodies that variably activated the endothelial m TORC pathway.

Shi T, Giannakopoulos B, Yan X,

et al.

DISCUSSION

YES

YES

YES

• The prevention of thrombosis is a major therapeutic goal in patients with the antiphospholipid syndrome. However, despite adequate anticoagulation, renal lesions develop in some patients and recur after transplantation, often leading to graft loss.

Nochy D, Daugas E, Droz

D, et al.

• Our data suggest that inhibition of the m TORC pathway in kidney-transplant recipients who have antiphospholipid antibodies protects the transplanted graft loss by preventing the development of intimal hyperplasia.

Canaud G, Bienaimé F,

Noël LH, et al.

• The fact that m TORC was predominantly activated in vessels from patients with antiphospholipid syndrome nephropathy suggets a pleiotropic effect of m TORC function in renal pathophysiology

Canaud G, Knebelmann B, Harris

PC, et al. Serra AL, Poster D,

Kistler AD, et al.Gödel M, Hartleben B,

Herbach N, et al.

DISCUSSION

YES

YES

YES

CONCLUSIONIn my opinion, the

research on this syndrome was very broad in patients with SLE, renal disease and heart disease; but I suggest that they should investigate more too on patients during pregnancy or lactation with the risks.

Still much to know about hypercoagulation effect of these patients and their control involves much effort.

Delving more about why some patients with these circulating antibodies do not develop the syndrome

CONCLUSION

Despite the variability of groups, in order to find the relationship between the via and the disease in question was achieved.